Switch mounting for electric drills



Aug. 21,' 1945. F, P. FORSS SWITl'I MOUNTING FOR ELECTRIC DRIKLLS- Filednec. so, 19,43 2 rSmeets-sheetl 1 .wm m n rrrrrrr Aug. 21, 1945. F. P.FORSS SWITCH MOUNTING FOR-ELECTRIC DRILLS Filed Dec. zo, 1945 2Sheets-Sheet `2 INVENTOR.

/k/r/f/of fom:

Patented Aug. 2l, 1945 UNITED STATES ...PATENT lori-ice SWITCH .MOUNTINGFORELECTRIC DRILLS Frtliiof- Pi Forss; Aurorailll.; assignor. toIndependent PneumaticY Tool Company, Chicago, IIL,- a. corporation of.Delawaret Application December 30, 1943', Serial No. 516,202

` 9.*Glai'ms. (Cl 172--36.).

This invention. relates to portable power operated electric drills` andlike tools.

The invention concerns the switch mountingy in. the handles of suchtool's and includes among.

its objects .the following:

To. provide `the handle sectionofthe tool withv opposed front and rearopenings whereby the connected switch device and its operable triggerblock.may. beinserted as-a unit` into. the handle.`

through the rear openingwiththe. trigger block extending into lthefrontopening;

To provide a clamp forthe supply cable for the.

tool motor supported by the toolt handle whereby` the. supply cable maybe connected with the.

handle separate from theswitch device and thus.

allow the latter and its oonnectedtriggerfhlock end of. the handlesection, the supply cable for the motor being omitted;

Fig. 6 yis a.. view similar to that of Fig. 1 with the switch deviceandithe trigger blockl assembly inthe .initial position of insertingtheunit into thefhandleofthe tool; y

Fig.y '7 is a rearend .view ofthe tool; and y Fig.. 8.*is. asimilar viewwith the cover plate for' the. handlefremoved. for. the. purpose ofillustrato be inserted into the handle throughsaid rearV openingindependently of thesupply cable;

To provide an` arrangement whereby the switch device in. the initialposition. of. inserting'. the.

switch device and its connected trigger bloclcmay be positioned outsideof thehandle adyacent to when the. latter is of the depending, .pistolgrip type, and. to clamp a-reinforcing sleeve tothe handle. about thesupply cable. where. it extends out of the handle to protect the cable.

The invention. consists further inthe features of constructionhereinafter shown and described.

In the accompanying drawings- Fig. 1 is a side View of a. portableelectrically motor driven drill constructed in accordance with myinvention, the. handlesection at therear end of the tool andtheladjoining portion'of the motor enclosing sectionof the tool housinglbeing broken away and in section, respectively, for the purpose ofillustration ;l

. Fig. 2. is a. horizontalk sectional view taken ontion. y

As shown in the drawings, the single housing" which encloses the toolmotor and the motor Switch and provides a handle for. the toolis in theform` of'. metal. casting fashioned to provide an v-integrally connectedmotor enclosing section I and-l a dependingy pistol grip. handle section2'at" the. rear end. ofthe tool. The housingI section" mounts anelectricmotor 3' for the tool and which motor has. an armature shaft. 4journalled at its rear end in a rollerbearing 5 mounted in the rear Wallportion. 6` of thehousing casting above the handle section 2 as shown inFig. 1.

Secured. by suitable fastening screws to the frontend '.of. the housingsection I in closing relation therewith is a gear reducing unit 1supportingthe front -end of the motor shaft 4 in a. suitable ball.bearing journalv (not shown) and mounting, the requisite gears fordriving the tool spindle 8from. the motor shaft 4 as in drills orlike-ltoolslas. the` character herein shown, The toolspindle 8isjournalled in the unit I and supports va chuck 9. at the front endofthe tool.

The housing section Iv is cylindrical. and en- ,closes the fanV element(not shown) driven by the line. 2 2 of Fig. 1 to show certain details ofcon struction;

FigA 3 is. asimilar sectional view taken on line w motor-shaftlforeoolingthe. motor and discharging through'slots. or. openings I0provided between the frontend of the housing. section I and thecontiguous portion of the unit I as. shown. in Fig. 1. The.v air. inlet.for the fan is. locatedat. the rear. endA of the tool .and is:preferably inthe. form of slotsY II, II in the housing section` Ionoppositesides .ofthe .bearing 5.,

The'rhandle section 2is hollow and is closed. at its opposite sides byside walls I2., I2 of. the handle casting` and on. its front side rbythe front wall I3 of .the handle casting. The rear side of the .handleis made with. an opening I4 and whichl opening has the width of thehandle between its side walls I2 and' extends along the handle forsubstantially the full length thereof .asvshown in- Fig. 8. cover.plate. I-5 which may be made in the form .nd .llas shown herein.

Theeopening I4 isnormally closed by a.

Located within the handle section 2 is a switch and operable triggerunit comprising a switch device I8 and a connected trigger block I9. Thelatter is received in a rectangular slot or opening 29 provided in thefront wall I3 cf the handle section immediately below the motorenclosing section I as shown in Figs. l and 6. The trigger block I9conforms to the shape of the front opening 2D and is slidably mountedtherein to be pressed inwardly to close the switch device to completethe electric circuit to the motor 3 for operating the same. When thetrigger block I9 is released, the spring tension of the switch device I8opens the switch to stop the motor and projects the trigger blockoutwardly into its normal position as shown in Fig. l.

The switch device I8 is of a conventional type and embodies a springtension to automatically open it. Hence. it is a self opening switch andits outer casing is rectangular in shape and of a size to easily fitwithin the handle section 2, pass ing through the rear opening I4. Thesuperstructure 2l of the switch device I8 mounts an actuating lever 22on a fulcrum pin 23 about which is a coiled spring 24 which moves theouter end 25 of the lever 22 outwardly when the trigger is released andthe switch opens. The outer end 25 of the lever 22 is slotted as at 25to receive a cross-pin 21 which permanently connects the lever 22 to theinner end of the trigger block I9. The lever 22 works in a slot 28 atthe -inner end of the trigger block and maintains the parts in operativerelation.

The switch device I8is held in place within the handle section 2 by thecover plate I5 when the latter is secured by the screws I6, I1 to thehandle section over the rear opening I4. The cover plate I has integralside lugs 29, 29 which bear against the rear surface of the switchcasing I8 to aid in holding the latter and the trigger block I9 inoperative positions in the handle section as shown in Fig. 3. Said plateI5 has an additional lug formation 30 to bear against the rear face ofthe switch casing I8 and mounts a fastening screw 3| which screws into atapped lug 32 carried by the switch structure. The lug 32 isnon-circular and ts within a like-shaped recess in the lug 30 on thecover plate i5 as shown herein. The lugs 29 on the cover plate I5 haveprojections 33, 33 to fit between the switch casing I8 and the adjacentside walls I2 of the handle section 2 to assist in positioning the partsand prevent displacement of the switch device when secured in the handlesection 2. The cover plate I5 has additional lugs 34, 34 to center theplate in applying the same in closing relation to the handle section. Ashield element 35 of paper is placed over the rear side of the switchdevice as a protector.

In mounting the switch device I8 within the tool handle 2, the supplycable 35 for the tool motor 3 is first secured within the handle sectionadjacent its lower or butt end by cable clamp there provided. This clampin the embodiment shown has a xed member 31 cast integral with thehandle section 2 between its side walls I2 and a removable member 38which is secured to the xed member by fastening screws 39, 39 as shownin Fig. 3. These members 31, 38 are recessed to lit about and clamp thecable 3S to the handle section 2. The member 38 is located within thehandle section and is enclosed by the cover plate I5 when the latter issecured in place. The clamping member 38 has a tapped lug 40 to receivethe lower screw I1 for the cover plate I5.

The lower or butt end of the handle section 2 is closed on the frontside of the cable 3B by an integral inwardly extending wall portion 4Iwhich fits against a similar wall portion 42 cast integral with thelower end of the cover plate I5. These wall portions 40, 4I close thelower or butt end of the tool handle 2 when the parts are assembled anddefine an opening 43 for the cable to extend into the handle.

A tubular reinforcing sleeve 44 is provided for the cable where thecable extends out of the handle section 2. This sleeve 44 is of rubberor other flexible material like the cable and has a diameter to t withinthe opening 43 as provided in the wall portions 4I, 42. The upper end ofthe sleeve 44 is enlarged in the form of a bead 45 which ts in the space46 between the wall portions 4I, 42 and the cable clamp members 31, 38.Hence, the sleeve 44 is clamped in place by the handle and the coverplate members and protects the cable.

After the cable 36 is clamped within the handle section 2 by the cableclamp, the switch device I8 and its connected trigger block I9 as' aunit are inserted into the handle section 2 through the rear opening I4with the trigger block extending into the opposed front opening 20.rI'he initial position of the parts is shown in Fig. 6 and while theswitch device I8 is positioned outside the handle section 2 as shown inFig. 6 the wiring connections between the motor 3 and the cable 36 andthe switch device I8 are made. The motor 3 in the embodiment shown is ofthe three phase induction type and has its leads 41, 41 connected to theupper terminals 43, 48 of the switch device I8. The cable leads 49, 49are con nected to the lower teminals `50, 50 of the switch device I8 asshown in Fig. 6. The third lead 5| of the motor is connected to thethird lead 52 of the cable and the ground lead 53 of the cable isconnected to the handle terminal 54 provided for such lead. Theterminals 48, 5D of the switch device are usually of the screw type andwith the switch device positioned outside of the handle section whilethe wiring connections are being made such terminals may be readily andeasily engaged by a screw driver without interference by the toolhousing.

When the wiring connections are completed, the leads are adjusted forentry into the handle section 2 as the switch device is pushed into thehandle. The connected side leads 5I, 52 may be located along one side ofthe switch device. The cover plate I5 is now applied and clamped inplace and holds the switch device and the trigger block in theiroperative positions within the handle. The trigger block normallyprojects through the iront opening 2U and is positioned to be operatedby a finger of the hand of the operator holding the tool about the griphandle 2,

As long as the trigger block I9 is held in its depressed or inwardposition the motor 3 is maintained in operation. Releasing the triggerblock I9 causes the spring 24 to project it outwardly to its normalposition and the switch device I8 automatically opens to cut the currentsupply to the motor. The cover plate I5 being secured to the handlesection and the switch device I8 being secured to the cover plate theswitch device resists the inward pressure on the trigger block in theoperation of the tool.

With a switch mounting of the character shown and described, the casingrfor the tool can be made in the form of a single housing with integralsections I and 2 for enclosing the motor and theswitch,respectively,-thus simplifying the construction of the tool andin addition providingthexhandle=sectionin the form of depending,pistolgrip, elementat the Vrearend o1' thetoolior conveniently .holdingand-manipulatingy thersame. Witha single housing, the outer for.forwarder-indio! 'the motor enclosing section I can `be madeopenv sothat the motor 3 and its rear bearing maybe inserted ythrough'the openfrontend oftthe .housing in assemblying-the tool.

With the handle section v2 being .hollow and having an opening I4 onitsArear .sidetheswitch deviceand its connected trigger block can beinserted into the handle section ein the manner herein vdescribed withthe .trigger block vfitting :in its slideway at theiront opening ofethehandle. The connected relation ofthe switch device and the trigger blockisestablishedbefore these parts are inserted into the handle section andhence no effort is required on 4behalf of the assembler to hold theparts in operative relation while the wiring connections are madebetween the switch device-and the cable. Moreoverfthe cable is fastenedto the handle prior to the insertion of the switch device and thetrigger block unit into the handle and these parts can be inserted intothe handle independently of the supply cable. The switch mounting shownand described is simple in construction and contrila'ites to feaseandspeed in assembling of the-tool construction.

The cover plate I5 is provided with a number of air intake slots 55 forthecooling system for the tool. Vice I8 and are preferably covered withawire screen 56 on the inside of the cover.

Said slots are located below the switch de- The details of constructionand arrangement of parts shown and described may be variously changedand modified without departing from the spirit and scope `of myinvention, except as .pointed out in the annexed claims.

I claim as my invention:

1. A portable power operated electrictool of the character describedcomprising, an electric motor and a spindle driven thereby, a toolhousing having a motor enclosing and supporting section and a hollowhandle section at the rear end of the tool, said handle section havingopposed openings, a supply cable for the motor secured to the handlesection, a switch device and an operable trigger block thereforinsertable as a unit into the handle through one of said openings withthe trigger block extendinginto the other of said openings, whereby saidswitch device with its trigger block in its associated opening may bepositioned outside of the handle section at the opening through whichthe switch device is inserted for connecting the motor and cable leads,respectively thereto, and a cover plate secured to the handle sectionover said last mentioned opening for holding the switch device and thetrigger block in operative positions in the handle.

2. A portable power operated electric tool of the character describedcomprising, an electric motor and a spindle driven thereby, a toolhousing hav- `ing a motor enclosing and supporting section and a hollow,depending, grip handle section at the rear end of the tool, said handlesection having opposed front and rear openings, a supply cable for themotor secured to the handle section, a switch device and an operabletrigger block therefor insertable as a unit into the handle through saidrear opening with the trigger block in the front opening, whereby saidswitch device with its trigger block in said front opening may bepositioned outside the handle section at said rear opening forconnecting the motor and cable leads, respectively thereto, .and .a.cover plate secured .to the 'handle section over .said vrear openinglfor holding the switch device and the trigger block in opera-tivepositions in the handle. f

3. A portable power operated electric tool of the fcharacter describedcomprising, an electric motor and aspindle driven-thereby, a toolhousing having la motor enclosing and supporting section anda hollow,depending, grip handle section at therear end of the tool, said handlesection having .opposed front and rear openings, a supply cable for themotor and securedto the handle section, ya permanently connected switchdevice and an operable trigger block therefor insertable as a unit intothe handle section through said rear opening with thetrigger blockextending into said front opening, .whereby said switch device with itstrigger block in the front opening may be positioned outside the handlesection at said rear opening forconnecting the motor and cable leads,respectively, thereto, and a cover plate secured to thehandle sectionover said rear opening for holding :the switch dewce .and the triggerblock in operative positions within the handle.

4. A portable power operated electric tool of the character describedcomprising, an electric motor and a spindle driven thereby, a toolhousing having amotor enclosing and supporting section and a hollow,depending, grip handle section at the rear end of the tool, a supplycable for the motor, a cable clamp supported by the handle section forsecuring the cable thereto, a permanently connected switch device and anoperable trigger block therefor insertable as a unit into the handlesection through said rear opening with the trigger block extending intosaid frontopening, whereby Vsaid switch device with its trigger block insaid front opening may be positioned outside the handle at said rearopening for connecting ythe motor and the cable leads, respectively,thereto, and a cover plate secured to the handle section over said rearopening for holding the switch device andthe trigger block in operativepositions in the handle.

5. A portable power operated electric tool of the y character describedcomprising, an electric motor and a spindle driven thereby, a toolhousing having a motor enclosing and supportingl section and a hollow,depending, grip handle section at the rear end of the tool, said handlesection having opposed openings, a supply cable yfor the motor, a switchdevice and a connected operable trigger block therefor, a cable clampsupported by the handle section for securing the cable thereto, saidswitch device and connected trigger block` insertable as a unit into thehandle section through one of said openings independently of the cablewith the trigger block extending into the other of said openings,whereby said switch device may be connected to motor and the cable leadsWhile positioned outside the handle section prior to inserting theswitch device into the handle, and a cover plate secured to thehandlesection over the opening through which the switch device isinserted for holding the switch device and the trigger block inoperative positions in the handle.

6. A portable power operated electric tool of the character describedcomprising, an electric motor and a spindle driven thereby, a toolhousing having a motor enclosing and supporting section and a hollow,depending, grip handle section at the rear end of the tool, said handlesection having front and rear openings, a connected switch device and anoperable trigger block therefor inrespectively, and a cover platesecured to the` handle section over said rear opening for hold-- ing theswitch device and the trigger block in operative positions in thehandle, said handle section and the cover plate having -inwardly eintending wall portions closing the lower end of the handle and definingan opening for the cable to extend into said handle.

'7. A portable power operated electric tool ol the character describedcomprising, an electric motor and a spindle driven thereby, a toolhousing having a motor enclosing and supporting section and a hollow,depending, grip handle section at the rear end of the tool, said handlesection having iront and rear openings, a connected switch device and anoperable trigger block therefor insertable as a unit into the handlesection through said rear opening with the trigger blocl; extending intosaid front opening, a supply cable for the motor', a cable clampsupported by the handle section adjacent the lower end thereof, saidswitch device being connected to the motor and the cable leads,respectively, a cover plato secured to the handle section over Said rearopen ing for holding the switch device and the trigger block inoperative positions in said handle, a reinforcing sleeve about thecable, and said cover plate and said handle section having inwardlyextending wall portions for closing the lower end of the handle sectionand clamping the reinforcing sleeve in position at the lower end of thehandle.

8. A portable power operated electric tool oi the character describedcomprising, an electric motor and a spindle driven thereby, a toolhousing having a motor 'enclosing and supporting section and a hollow,depending, grip handle section at the rear end of the tool, said handlesection Ahaving front and rear openings, a connectedl switch device andan operable trigger block therefor insertable as a unit into the handlesection through said rear opening with the trigger block extending intothe front opening, a supply cable for the motor, a cable clamp supportedby the handle section adjacent the lower end thereof, said switch devicebeing connected to the motor and cable leads, respectively, a coverplate secured to the handle section over said rear opening for holdingthe switch device and the trigger block in operative positions in thehandle, a reinforcing sleeve for the cable, and said cover plate andsaid handle section having inwardly extending wall portions spaced fromthe cable clamp for closing the lower end of the handle section and forsecuring the beaded upper end of the cable therebetween.

9. A portable power operated electric tool of the character describedcomprising, an electric motor and a spindle driven thereby, a toolhousing having a motor enclosing and supporting section and a hollowhandle section at the rear end of the tool, said handle section havingopposed openings, a switch device and an operable trigger block thereforinsertable into the handle section through one of said openings with thetrigger block extending into the other of said openings, a supply cablefor the motor, a cable clamp supported by the handle section forsecuring the cable thereto, said switch device being connected to themotor and the cable leads, respectively, a cover plate for -closing theopening through which the switch device and the trigger block areinserted, and fastening screws securing the cover plate to the handlesection and the switch device, respectively, one of the screws engagingthe cable clamp.

FRITHIOF P. FORSS.

